10.9.1 Purpose
Business rules analysis is used to identify, express, validate, refine, and organize the rules that shape day-to-day business behavior and guide operational business decision making.
10.9.2 Description
Business policies and rules guide the day-to-day operation of the business and its processes, and shape operational business decisions. A business policy is a directive concerned with broadly controlling, influencing, or regulating the actions of an enterprise and the people in it. A business rule is a specific, testable directive that serves as a criterion for guiding behavior, shaping judgments, or making decisions. A business rule must be practicable (needing no further interpretation for use by people in the business) and is always under the control of the business.
Analysis of business rules involves capturing business rules from sources, expressing them clearly, validating them with stakeholders, refining them to best align with business goals, and organizing them so they can be effectively managed and reused. Sources of business rules may be explicit (for example, documented business policies, regulations, or contracts) or tacit (for example, undocumented stakeholder know-how, generally accepted business practices, or norms of the corporate culture). Business rules should be explicit, specific, clear, accessible, and single sourced. Basic principles for business rules include:
- basing them on standard business vocabulary to enable domain subject matter experts to validate them,
- expressing them separately from how they will be enforced,
- defining them at the atomic level and in declarative format,
- separating them from processes they support or constrain,
- mapping them to decisions the rule supports or constrains, and
- maintaining them in a manner such that they can be monitored and adapted as business circumstances evolve over time.
A set of rules for making an operational business decision may be expressed as a decision table or decision tree, as described in Decision Analysis (p. 261). The number of rules in such a set can be quite large, with a high level of complexity.
10.9.3 Elements
Business rules require consistent use of business terms, a glossary of definitions for the underlying business concepts, and an understanding of the structural connections among the concepts. Reuse of existing terminology from external industry associations or internal business glossaries is often advised. Sometimes
definitions and structures from data dictionaries or data models can be helpful (see Data Dictionary (p. 247) and Data Modelling (p. 256)).
Business rules should be expressed and managed independently of any implementation technology since they need to be available for reference by businesspeople. In addition, they
sometimes will be implemented in multiple platforms or software components. There are frequently exceptions to business rules; these should be treated simply as additional business rules. Existing business rules should be challenged to ensure they align with business goals and remain relevant, especially when new solutions emerge.
.1 Definitional Rules
Definitional rules shape concepts, or produce knowledge or information. They indicate something that is necessarily true (or untrue) about some concept, thereby supplementing its definition. In contrast to behavioral rules, which are about the behavior of people, definitional rules represent operational knowledge of the organization. Definitional rules cannot be violated but they can be misapplied. An example of a definitional rule is:
A customer must be considered a Preferred Customer if they place more than 10 orders per month.
Definitional rules often prescribe how information may be derived, inferred or calculated based on information available to the business. An inference or calculation may be the result of multiple rules, each building on something inferred or calculated by some other(s). Sets of definitional rules are often used to make operational business decisions during some process or upon some event.
An example of a calculation rule is:
An order’s local jurisdiction tax amount must be calculated as (sum of the prices of all the order’s taxable ordered items) × local jurisdiction tax rate amount.
.2 Behavioral Rules
Behavioral rules are people rules-even if the behavior is automated. Behavioral rules serve to shape (govern) day-to-day business activity. They do so by placing some obligation or prohibition on conduct, action, practice, or procedure.
Behavioral rules are rules the organization chooses to enforce as a matter of policy, often to reduce risk or enhance productivity. They frequently make use of the information or knowledge produced by definitional rules (which are about shaping knowledge or information). Behavioral rules are intended to guide the actions of people working within the organization, or people who interact with it.
They may oblige individuals to perform actions in a certain way, prevent them from carrying out actions, or prescribe the conditions under which something can be correctly done. An example of a behavioral rule is:
An order must not be placed when the billing address provided by the customer does not match the address on file with the credit card provider.
In contrast to definitional rules, behavioral rules are rules that can be violated directly. By definition, it is always possible to violate a behavioral rule – even if there are no circumstances under which the organization would approve that, and despite the fact that the organization takes extraordinary precautions in its solution to prevent it. Because of this, further analysis should be conducted to determine how strictly the rule needs to be enforced, what kinds of sanctions should be imposed when it is violated, and what additional responses to a violation might be appropriate. Such analysis often leads to specification of additional rules.
Various levels of enforcement may be specified for a behavioral rule. For example:
- Allow no violations (strictly enforced).
- Override by authorized actor.
- Override with explanation.
- No active enforcement.
A behavioral rule for which there is no active enforcement is simply a guideline that suggests preferred or optimal business behavior.
10.9.4 Usage Considerations
.1 Strengths
- When enforced and managed by a single enterprise-wide engine, changes to business rules can be implemented quickly.
- A centralized repository creates the ability to reuse business rules across an organization.
- Business rules provide structure to govern business behaviors.
- Clearly defining and managing business rules allows organizations to make changes to policy without altering processes or systems.
.2 Limitations
- Organizations may produce lengthy lists of ambiguous business rules.
- Business rules can contradict one another or produce unanticipated results when combined unless validated against one another.
- If available vocabulary is insufficiently rich, not business-friendly, or poorly defined and organized, resulting business rules will be inaccurate or contradictory.
